Modern emergency medical practice strives to provide the most advanced and timely diagnosis and treatment as possible, since time factor is often crucial to the successful clinical outcomes.
One of the sudden critical health crises is cardiac ventricular fibrillation (VF) which is invariably fatal unless treated promptly. The common way to treat VF is to administer an electric pulse to the heart which shocks the heart muscle and induces it to revert to its normal contraction pattern. This procedure is called defibrillation and is effected by an apparatus called ‘defibrillator’.
There are two types of defibrillators: the external and internal, the latter implanted into a patient's body.
External defibrillators are relatively large and contain a large battery pack and a high voltage generator. The weight of an external defibrillator is in the order of 2-3 lbs (1-1.5 kg). The generated high voltage pulse is administered to a patient via two large conductive paddles positioned on his chest and side, respectively. The defibrillator batteries have to be periodically tested and if of the rechargeable type, recharged, which adds to the maintenance labor and expenses for the system's owner.
The implantable defibrillator, being very small and light is permanently surgically implanted into a patient's body, and its electrical lead is inserted into the heart. The outer case of the device is made of metal and acts as a second electrode to complete the path of electrical current through the heart. The implantable defibrillators are used in patients with chronic cardiac disease and their implantation requires a major surgical procedure in a hospital setting.
In an emergency situation providing an external defibrillator in a timely manner can be problematic, since due to its size and weight it presents a carry challenge to first-response medical personnel who are frequently over-burdened with other equipment and may not have an external defibrillator in their medical kit. Also, some first-responders, such as for example motorcycle patrol policemen may not carry a defibrillator due to the limited carry space on their motorcycles. Waiting for the response team with a defibrillator to arrive may spell death for the VF sufferer. On the other hand, to implant a small defibrillator under field conditions and within an extremely short ‘window of opportunity’ is not feasible.
Still, having a defibrillation capability ‘on-hand’ in an emergency is very desirable in view of its potential in saving lives.
In addition, it would be desirable to have a defibrillator system of the ‘store-and-forget’ type: the one not requiring any service, like periodic testing or re-charging of the batteries.